Bistable safety dispensing valve for fluid dispensers

ABSTRACT

A VALVE STEM OF A DISPENSING VALVE FOR A PRESSURIZED DISPENSER IS COUPLED TO A BISTABLE SPRING FOR MOVEMENT TO A VENT POSITION WHEN THE PRESSURE WITHIN THE DISPENSER EXCEEDS NORMAL DISPENSING PRESSURES. THE VALVE STEM IS MAINTAINED IN THE VENT POSITION BY THE BISTABLE SPRING, WHICH IS IN ONE OF ITS STABLE POSITIONS, NOTWITHSTANDING A DROP IN PRESSURE WITHIN A DISPENSER. AT NORMAL OPERATING PRESSURES, THE BISTABLE SPRING IS IN ITS ALTERNATE STABLE POSITION AND RESISTS DISPENSER PRESSURE TO MAINTAIN THE VALVE STEM OUT OF THE VENT POSITION. UNDER NORMAL PRESSURES, THE VALVE IS OPERATED TO DISPENSE PRODUCT BY FINGER PRESSURE APPLIED TO THE VALVE STEM AGAINST THE SPRING TO COMMUNICATE A PRODUCT PORT LEADING TO A PRODUCT PASSAGE WITH THE INTERIOR OF THE DISPENSER. ACTUATION MAY BE DONE BY APPLYING PRESSURE EITHER NORMAL TO THE VALVE STEM OR AXIALLY ALONG THE VALVE STEM.

May 23 1972 R. K. BRUCE 3,664,557

BISTABLE SAFETY DIvSPENSING VALVE FOR FLUID DISPENSERS Filea'Nov. 13, 1970 United States Patent O U.S. Cl. 222-397 18 Claims ABSTRACT F THE DISCLOSURE A valve stern of a dispensing valve for a pressurized dispenser is coupled to a ibistable spring for movement to a vent position when the pressure within the dispenser exceeds normal dispensing pressures. The valve stem is maintained in the vent position by the bistable spring, which is in one of its stable positions, notwithstanding a drop in pressure Within a dispenser. At normal operating pressures, the bistable spring is in its alternate stable position and resists dispenser pressure to maintain the valve stem out of the vent position. Under normal pressures, the valve is operated to dispense product by 4finger pressure applied to the valve stem against the spring to communicate a product port leading to a product passage with the interior of the dispenser. Actuation may be done by applying pressure either normal to the valve stem or axially along the valve stern.

BACKGROUND OF THE INVENTION This invention relates in general to the art of fluid dispensers and, more in particular, to a safety dispensing valve which responds to an excessive pressure in a fluid dispenser to vent the dispensers interior and maintain communication between the dispensers interior and atmosphere regardless of a subsequent drop of pressure within the dispenser.

Pressurized fluid dispensers are extremely popular. These dispensers maintain a product to be dispensed under pressure and sealed within them. A dispensing valve is employed to selectively discharged the product.

When heated, the pressure within such a dispenser increases. The pressure often increases to such an extent that the dispenser will catastrophically exploded. This explosion hazard is present whether the dispenser contains product or whether it is empty, for in the latter instance there is suicient gas remaining in the dispenser which, when heated, can reach a pressure sufficient to cause an explosion. Accidents are not uncommon, for example, where a dispenser is in advertently placed close to a source of heat. Even when the dispenser is thrown away, it is not uncommon that it iinds itself in an open ire or a furnace with the inevitable result of an explosion and possible injury to people close by.

To avoid explosion hazards, several concepts have been proposed. One of these concepts is to have a weakened section in the wall of the dispenser. The weakened section is designed to relieve the pressure within the dispenser, when it becomes sufficiently high, by opening its interior to atmosphere. This concept generally takes two forms. One form is purely pressure sensitive. The dispenser wall is weakened to either allow its front section to blow out or the dispenser to separate in half. The other form employs a low melting point plug which, upon reaching a sufficiently high temperature, melts to communicate the interior of the 'dispenser with atmosphere. Both devices vent the interior of a dispenser completely and very rapidly, which can be hazardous under certain conditions; for example, if the contents of a dispenser are flammable their escape can results in a amethrower effect. Nonetheless, the complete venting of a container inherent in these con- 3,664,557 Patented May 23, 1972 ICC cepts has an advantage in at least one particular to be discussed subsequently.

lAnother concept is to break the dispensing valve after the dispenser is empty in such a manner as to vent the dispensers interior. This concept does not guard against the explosing hazard while the dispenser still contains product. In addition, inadvertent destruction of the dispensing valve, while product remains, is itself a hazard because the product will escape very rapidly. Moreover, such as inadvertent destruction is wasteful of the product.

Still another concept envisions the freezing of an empty pressurized dispenser and then puncturing the dispenser. To avoid an explosion hazard by having each and every dispenser frozen and punctured by its user is an extremely unreliable and arduous way to safety. Moreover, the concept does not avoid the hazard of explosion while product yet remains in the dispenser.

In U.S. Pat. 3,519,172 to John K. Bruce, a dispensing valve is described for venting the interior of a pressurized dispenser gradually and reliably without user attention when the dispenser is subjected to heat. The patentee employs a spring which acts on a valve stem to resist dispenser pressure and prevent dispenser venting until a predetermined excessive pressure is reached. In the patentees valve, when the pressure in the dispenser drops below the excessive pressure, venting stops.

There is at least one condition where all the contents of a dispenser should be vented after an excessive pressure is reached. This condition exists in a dispenser having a seam, normally longitudinal, which is sealed with a eutectic material such as solder. In a tire ra condition can exist where the seam is exposed directly to a high temperature but the pressure buildup in the dispenser is at a relatively low rate. In the patentees valve the valve stem would move to vent the interior of excessive pressure but then moves back to a position where venting is terminated until the pressure once again builds up in the dispenser. In short, the dispensing valve will open and close repeatedly. If, however, the eutectic material melts, the contents of the dispenser, under a pressure below that required to vent, Will explode the dispenser at the seam. Thus there is a need for an improvement in the dispensmg valve described in U.S. Pat. 3,519,172 which, when subjected to a predetermined venting pressure will open to vent the interior of the dispenser of excessive pressure and remain open regardless of a drop in the pressure within the dispenser.

SUMMARY OF THE INVENTION The present invention provides an improvement in the dispensing valve and dispensing valve-dispenser combination described in U.S. Pat. 3,519,172. The improvement resides in means for maintaining a valve stem in a venting position to completely exhaust the contents of the dispenser once a predetermined pressure within a dispenser is reached. Stated differently, the dispensing valve of the present invention is operable to communicate the interior of the dispenser with atmosphere when a predetermined excessive pressure within a dispenser is reached and thereafter to maintain communication between the interior of the dispenser and atmosphere regardless of a drop in interior pressure.

A specific form of the invention employs a bistable safety dispensing valve for a iluid dispenser having a valve stem, means for mounting the valve stem to a dispenser, and a bistable spring. The bistable spring in one of its stable positions keeps the valve stem in position for selective actuation of the valve and in its second stable position keeps the valve stem in a position to continuously vent the interior of the dispenser. The bistable spring is responsive to a predetermined excessive pressure to shift from its first to its second stable position.

An upper portion of the valve stem has an axially oriented product passage for dispensing product. A lower portion of the valve stem has an axially oriented vent passage which is always open to the interior of the dispenser. A vent port into the vent passage is normally disposed out of communication with the exterior of the dispenser but, when the predetermined excessive pressure is reached, the valve stem moves to communicate the vent port with atmosphere and effect venting of the dispensers interior. A product port through the wall of the upper portion is disposed such that upon actuation of the valve stem, as by horizontal or vertical finger pressure on the stem, the port communicates with the interior of the dispenser for the discharge of product out the product passage. When not actuated, the product port is disposed out of communication with the interior of the dispenser so that no product can leave the dispenser. The product and vent passages are separated by a partition to prevent direct communication between them.

The mounting means receives the valve stem with the vent port normally out of communication with the dispensers exterior, the vent passage always in communication with the dispenrsers interior, the product port normally out of communication with the dispensers interior, and the product passage extending to the dispensers exterior.

In a presently preferred embodiment of the present invention, the mounting means includes a yieldable seal which receives the valve stem. The seal can be displaced laterally upon the tilting of the valve stem for the communication of the product port within the interior of the dispenser. Alternatively, the seal and the bistable spring permit inward movement of the stem in response to a force applied axially on the stem to communicate the product passage through the product port with the dispensers interior for the discharge of product. A preferred form of the bistable spring comprises a disc-like plastic member molded integrally with the stem and having a curvature which reverses between the stable positions of the spring. For guiding the stem, the spring preferably has a skirt for guidance on the interior wall of a housing of the dispensing valve. The spring purchases on the bottom surface of the seal, but obviously can be purchased elsewhere. To accommodate material movement of the spring between its two stable positions holes are provided in the spring.

'In more specific form, the mounting means of the present invention has a valve cup for attaching the disi pensing valve to the dispenser. The valve cup has a recess which receives the yieldable seal and provides for the mounting of the housing. The recess, Which is disposed for facing the interior of the dispenser, receives the housing which, in turn, compressively loads the seal against the walls of the recess and the stem to prevent leak paths. A return spring, in addition to the bistable spring, may be provided between the housing and the valve stem to ensure that the product port is normally out of cornmunication with the dispensers interior.

The present invention retains the simplicity of construction and operation of the dispensing valve and dispenser described in U.S. Pat. 3,519,172. Thus the pressure vent port and the stem will rise in response to a pressure buildup within the dispenser beyond a predetermined limiting pressure to communicate the dispensers interior with atmosphere and relieve the pressure by discharging product. Because the vent port is carried by the valve stem, venting may be against an interior side wall of the valve cup. This feature effectively distributes the vented product into a small area and dissipates its force. The advantage of this feature is apparent when the product within the dispenser is flammable.

The dispensing valve of the present invention, however, has the advantage over the patentees dispensing valve of always maintaining the interior of the dispenser in communication with atmosphere once a predetermined pressure is reached. This advantage prevents the kind of explosion occasioned by the melting of the eutectic material of the seam of `a dispenser discussed in the background of the invention section of this specilication.

Relative to the concepts which preceded the valve described in the John K. Bruce patent, the valve of the present invention is pressure sensitive and therefore consumer attendance to safety is not required. It is also not necessary to freeze the dispenser and puncture it after its contents have been emptied or to fracture the dispensing valve to communicate the interior of the dispenser with atmosphere. As a consequence, the dispensing valve of the present invention is safe not only when product is within the dispenser, but when the dispenser is empty. Expensive and unpredictable weakened sections are avoided.

These and other features, aspects and advantages of the present invention will become more apparent from the following description, appended claims and drawlngs.

BRIEF DESCRIPTION OF THE FIGURES FIG. l is a generalized view of the dispensing valve and dispenser of the present invention;

FIG. 2 is a partial view, in half section, of the preferred form of the dispensing valve of the present invention;

FIG. 3 is a fragmentary view in half section showing the path of product as it is being discharged from the dispenser upon actuation of the valve; and

FIG. 4 shows how product is vented when excessive pressure is reached within the dispenser and the shift of the bistable spring from one of its stable positions to its alternate stable position.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. l depicts a container or dispenser 10 which has a dispensing Valve 12 mounted in its cover or dome 14. Except for the dispensing valve, the dispenser may be of standard construction. Typically, the dispenser has a hollow body portion 16 connected to cover 14 as by seam 18 and to a bottom cap 20 by seam 22. A valve cup 24 secured to cover 14 by a seam 26 actually carries dispensing valve 12. The dispenser is pressure tight. The product to be dispensed is contained in dispenser 10 under pressure. The product is dispensed through hand actuation of dispensing valve 12. The dispenser illustrated has a side seam, denoted by reference numeral 28, which includes a eutectic material such as solder.

FIG. 2 depicts in detail improved dispensing valve 12 of the present invention. In general, the dispensing valve includes a valve stem 30, a bistable positioning spring 32, a return spring 34, a gasket or seal 36, a housing 38, and valve cup 24. As will become more apparent as this description proceeds, biaxial actuation of the dispensing valve 12 to dispense product is possible and the valve relieves excess pressure within dispenser 10. By biaxial actuation, it is meant that finger pressure exerted on valve stem 30, through an actuator 42 mounted thereon, either normal to the axis of the stem or along the axis of the stern, will open the valve.

Stem 30 has an upper portion 44 and a lower portion 46. Upper portion 44 has a product passage 4S oriented on the longitudinal axis of the stem which is in communication with a dispensing orifice 50 of actuator 42. A product port 52 extends through the wall of upper portion 44 at a point within seal 36. With normal operating pressures in dispenser 10 and until the valve is actuated, product port 52 remains within seal 36. The position of the product port must be such that when the dispensing valve is actuated, the port sees the interior of the dispenser for the discharge of product, but when the dispensing valve is unactuated, the port is out of communication with the interior of the dispenser.

Lower portion 46 of valve stem 30 includes a vent passage 54 which extends along the axis of the stern downward towards the interior of dispenser 10. A pressure vent port 56 is at the upper end of vent passage 54 and extends through the wall of lower portion 46 to communicate the vent passage with the exterior of the stem. The pressure vent port normally resides within the interior of housing 38, but when an excessive pressure acts on stern 30, the port rises above the top of seal 36 to communicate the interior of the dispenser through vent passage 54 with atmosphere. The lower end of vent passage 54 is open for the continuous communication of -the passage with the interior of the dispenser. A partition 58 separates product passage 48 from vent passage 54.

Bistable spring -32 is Iintegral with stem 30. Inasmuch as it is preferred to have the stem of plastic material, the bistable spring can be molded with the stem. In any event, and as previously mentioned, the bistable spring has two stable positions. The first of these positions is shown in FIG. 2 and corresponds to a disposition of valve stem 30 under normal dispenser pressures. In this first stable position, vent port 56 is out of communication with the exterior of the dispenser and product port 52 is out of communication with the interior of the dispenser. In its first stable position, the bistable spring admits to actuation of the dispensing valve by linger pressure applied either normal to the longitudinal axis of valve stem 30 or along the longitudinal axis. With finger pressure applied normal to the axis, product port 52 communicates with the interior of the dispenser as is illustrated in FIG. 3, that is, the stem moves away from the bordering wall of seal 36 to a position where product port 52 communicates with the interior of the dispenser. Where axial finger pressure is applied, stem 30 is forced along its axis downwardly to communicate product port 52 with the interior of housing 38 and therefore the interior of dispenser 10.

FIG. 4 illustrates the alternate stable position of bistable spring 32 which corresponds to the vent position of the valve stem. In this position, vent passage 54 communicates with atmosphere through vent port 56, which is now exposed to atmosphere. Also, in this position, bistable spring 32 does not exert any force on the stern which would tend to retract the stem from its vent position to the unactuated position illustrated in FIG. 2. AS such, diminution of pressure within the dispenser does not affect the disposition of the valve stern and the vent port will always be in communication with atmosphere once the valve stem is in the vent position.

Proceeding with a detailed description of the present invention, housing 38 provides purchase for a conical return spring 34. The return spring is disposed to act between the housing and the valve stem. The function of return spring 34 is to assure the proper position of valve stem 30 after it has been actuated, typically by its axial depression. Another way of viewing the function of spring 34 is that is assures the overcoming of any static friction of seal 36 on the valve stem which after actuation might maintain the stem with the product port in communication with the dispensers interior. The spring is conical to avoid coil binding.

Housing 38 includes a generally right cylindrical upper portion 60 and a generally right cylindrical lower portion 62 of smaller diameter. The interior of the upper portion of the housing is hollow to accommodate product, return spring 34, bistable spring y32, and lower portion 46 of stem 30. Lower portion 62 of the housing may be used as a mount for dip tube. An axial passage 64 in thisV lower portion provides for product passage from the interior of dispenser to the volume within upper portion 60. An annular recess 66, at the junction between the upper and lo-Wer portions of the housing, receives and captures the base of return spring 34. The upper end of the upper portion of the housing compressibly engages seal 36 to cause the latter, in turn, to compressibly engage the bounding valve cup and stern to provide a seal against the passage of product out of the dispenser through a hole or opening 68 in valve cup 24 through which stem 30 extends. That is, the compressive engagement of seal 36 blocks product passage between the seal and the stem and along the interface between the seal and the valve cup.

Valve cup 24 has a generally toroidal channel 70 which is bounded by an exterior vertical wall '72 and an interior vertical wall 74.

An annular, outwardly extending radial crimp 76 is formed in wall 72 and bears on the interior surface of cover 14 to rmly secure valve cup 24 to the cover. The 'base of channel 70 is defined by an annular radial portion 78 which connects vertical walls 72 and 74. A radial portion 80 extends radially inward from the top of vertical wall 74. Hole 68 through which valve stem 30 extends is formed in radial portion 80 of the valve cup. The diameter of hole 68 relative to the diameter of valve stem 60 is suicient to provide a clearance for the stem to tilt, as is shown in FIG. 3.

Vertical Wall 74 includes a radially inward extending ange 82, which may be formed by crimping under a complementary flange 84 of housing 3-8, to securely hold the housing in place and to provide the means by which the compressive engagement of the upper portion of the housing and seal 36 is maintained.

The valve cup has an annular lip 86 which is crimped over a mating lip 88 of cover 14 and cooperates with crimp 76 to secure the cup to the cover.

Bistable spring 32 is integrally formed with valve stem 30. The bistable spring is disc-shaped. The spring in its unactuated position has a concave surface facing the bottom of seal 36. A skirt 90 of the spring is disposed for guidance along the interior vertical wall of upper portion 60 of housing 3K8. Skirt 90 engages the bottom of seal 36 for the purchase of the spring. A plurality of holes 92 in the spring provides space to accommodate material movement in the spring as it flexes from actuation of the dispensing valve, or as the spring moves from its 4first stable position to its second stable position.

As previously mentioned, passage 64 of housing 38 is in product communication with the interior of dispenser 10 and because of it, the interior of the housing is also in product communication with the interior of the dispenser. The product exerts pressure on stern 30 and tends to -drive the stem upward. The effective area of stem 30 which feels upward pressure is equal to the area of partition 58 and the cross-sectional area of the wall of lower portion 46 of the stem. Return spring 34 may also exert a slight upward force on the stem. In normal usage, bistable spring 32, in its first stable position shown in FIG. 2, will exert a force on stem 30 which is balanced by the pressure in the dispenser felt by this effective area and any force exerted lby spring 34.

Actuator 42 is secured to stem 30 as by a press fit. To index dispensing orifice 50 of the actuator on the same side of stem 30 as product port 52, the top of the stem and a recess in the actuator which receives the stem may be made such that the actuator can be placed on the stem only with the dispensing ori-lice aligned with the product port.

FIGS. 3 and 4 depict the operation of the improved dispensing valve of the present invention.

In lFIG. 3, stem 30` is in one of its actuated positions. In the particular one illustrated, the stem is tilted off the longitudinal axis of the dispenser, that is, it has been angularly displaced from the orientation it was in before actuation. In this actuated position, product passage 48 is open to the interior of housing 38 through product port 52 and product will be dispensed. lIt should be noted that seal 36 does not cover port 52 when the stem is tilted. During this mode of actuation, bistable spring 32 rliexes as is illustrated in FIG. 3 to resist the actuation force. Skirt 90 of the spring, where the spring is not being loaded, moves slightly away from the interior wall of upper portion 60 of housing 38 and from seal 36. As can be seen in FIG. 2, dispensing valve 12 can be actuated by forcing stem 30 inwardly along its longitudinal axis against the force of spring 34 and product pressure to lower product port 52 to a point within housing 38. When port 52 is within the housing, product communication into product passage 48 is effected and product will be discharged through dispensing orifice 50 of actuator 42.

As is illustrated in FIG. 4, when the pressure within dispenser 10 increases to predetermined excessive pressure, the pressure will act on stem 30 and against the force of spring 32 to raise the stern upward to a point where the force of the spring on the stem reverses to augment the pressure force and snap the stem into its vent position with pressure vent port 56` in communication with atmosphere. In the process, bistable spring 32 shifts from its rst to its second stable position. Vent port 56 will thereafter remain in communication with atmosphere and the interior of the dispenser will also remain in communication with atmosphere, notwithstanding any decrease in the pressure within the dispenser below the predetermined excessive pressure. Stated differently, spring 32 in its second stable position exerts a force on stern 30 which tends to keep the stem in its vent position. However, the friction between seal 36 and stem 30 keeps the valve stem in its vented position without spring 32 and product pressure. Spring 32 in its second stable position has its curvature reversed such that the surface facing the interior of the dispenser is concave.

With reference to lFIG. l, the advantage of having a valve stem, once in a vent position remain in that position, regardless of dispenser pressure, will be discussed. As brought out in the background of the invention section of this specification, there is the possibility that a dispenser will be exposed to a source of heat of suicient intensity to melt the eutectic material constituting the bond of seam 28. If valve stem 30 receded from the Veut position shown in FIG. 4 to the position shown in FIG. 2 with a diminution in pressure within the dispenser, there still could be a large amount of product within the dispenser. In the John K, Bruce patent previously referred to, the valve stem can repeatedly change its position between its vent and unactuated positions. With that construction and upon the melting of the eutectic material, the dispenser can explode with a considerable explosive force, notwithstanding the fact that pressure within the dispenser is within the normal operating range. With the present L) construction, all the product within the dispenser is vented once valve stem 30 reaches its vent position. Thus, the shortcomings of the John K. Bruce valve are overcome.

The present invention has been described with reference to certain preferred embodiments. The spirit and scope of the appended claims should not, however, be necessarily limited to the foregoing description.

What is claimed is:

1. A bistable safety dispensing valve for fluid dispensers of the type which contain a product to be dispensed under pressure within a predetermined normal pressure range comprising:

(a) a valve stem having a longitudinal axis, an upper portion having an axially oriented product passage, a lower portion having an axially oriented vent passage which has an opening for communicating the vent passage with the dispensers interior at all times, a product port through the wall of the upper portion into the product passage, a vent port through the wall of the lower portion into the vent passage and spaced longitudinally of the opening toward the upper portion, and a partition between the product passage and the vent passage to prevent direct cornmunication between them;

(b) means for mounting the dispensing valve to the dispenser such that the vent port is normally out of communication with the dispensers exterior, the vent passage is always in communication with the dispensers interior, the product port is normally out of communication with the dispensers interior, and the product passage extends to the dispensers exterior; and

' (c) bistable spring means having a rst and a second stable position, the bistable spring means being coupled to the valve stem such that:

(i) in the 'rst stable position the valve stem is maintained against normal pressures in the dispenser in an unactuated position with the product port out of communication with the dispensers interior and the vent port out of communication `with the dispensers exterior,

(ii) in the rst stable position upon the application of a dispensing force on the valve stem exteriorly of the dispenser the valve stem is displaced against the force of the bistable spring means to communicate the product port with the interior of the dispenser,

(iii) with the presence of a predetermined pressure in excess of the normal pressure within the dispensers interior, the valve stem is moved to a vent position with the dispensers exterior and the bistable spring means is moved to the second stable position; and

(iv) in the second stable position the valve stem is maintained in the vent position regardless of the pressure within the dispensers interior.

2. The bistable safety dispensing valve claimed in claim 1 wherein:

the bistable spring means includes a disc-shaped spring member integrally connected to the valve stem.

3. The bistable safety dispensing valve claimed in claim 2 wherein:

the disc-shaped spring member is disposed to act between the mounting means and the stem such that the curvature of the member reverses between its stable positions to provide a force on the valve stem to resist dispenser pressure in the rst stable position, and a force on the valve stem to augment dispenser pressure in the second stable position to maintain the valve stem in the vent position.

4. The bistable safety dispensing valve claimed in claim 3 wherein:

the disc-shaped spring member has a plurality of holes to accommodate movement of spring member material with movement of the spring.

5. The bistable safety dispensing valve claimed in claim 4 wherein:

(a) the mounting means includes a housing receiving the bistable spring and the lower portion of the valve stem; and

(b) the disc-shaped spring member includes a skirt disposed for guidance along the interior wall of the housing.

6. A bistable safety dispensing valve for fluid dispensers of the type which contain a product to lbe dispensed under pressure within a predetermined normal pressure range compnsmg:

(a) a valve stern having a longitudinal axis, an upper portion having an axially oriented product passage, a lower portion having an axially oriented vent passage which has an opening for communicating the vent passage with the dispensers interior at all times, a product port through the wall of the upper portion into the product passage, a vent port through the wall of the lower portion into the vent passage and spaced longitudinally of the opening toward the upper portion, and a partition between the product passage and the vent passage to prevent direct communication between them;

(b) means for mounting the dispensing valve to the dispenser such that the vent port is normally out of communication with the dispensers exterior, the vent passage is always in communication wtih the dispensers interior, the product port is normally out of communication with the dispensers interior, and the product passage extends to the dispensers exterior; and

(c) bistable spring means having a first and a second stable position, the bistable spring means being coupled to the valve stern such that:

(i) in the first stable position the valve stem is maintained against normal pressures in the dispenser in an unactuated position with the product port out of communication with the dispensers interior and the vent port out of communication with the dispensers exterior,

(ii) in the first stable position upon the application of a dispensing force on the valve stem exteriorly of the dispenser the valve stem is displaced against the force of the bistable spring means to communicate the product port with the interior of the dispenser,

(iii) with the presence of a predetermined pressure in excess of the normal pressure within the dispensers interior, the valve stem is moved to a vent position with the vent port in communication with the dispensers exterior and the bistable spring means is moved to the second stable position; and

(iv) in the second stable position the valve stern is maintained in the vent position regardless of the pressure within the dispensers interior.

7. The bistable safety dispensing valve claimed in claim 6 wherein:

the mounting means and bistable spring means are coupled to the valve stem such that with the bistable spring means in the first stable position the valve stern is capable of axial or angular actuation.

8. The bistable safety dispensing valve claimed in claim 6 wherein:

the mounting means and bistable spring means in the first stable position maintain the valve stem in a predetermined angular and axial orientation such that with the application of a dispensing force normal to the axis of the valve stem the valve stem is angularly displaced from the predetermined angular position to communicate the product port with the interior of the dispenser, and with the application of a dispensing force along the axis of the valve stem the valve stem is axially displaced from the predetermined axial position to communicate the product port with the interior of the dispenser.

9. The bistable safety dispensing valve claimed in claim 6 wherein:

the mounting means includes a seal of yieldable material in receipt of the valve stem for permitting axial or angular displacement thereof to communicate the product port with the interior of the dispenser.

10. The bistable safety dispensing valve claimed in claim 9 wherein:

the bistable spring comprises a disc-shaped spring member disposed to act between the valve stem and the mounting means such that the curvature of the spring member reverses between its stable positions to provide a force on the valve stem to resist dispenser pressure in the first stable position and a force on the valve stem to augment dispenser pressure in the second stable position to maintain the valve stem in the vent position.

11. In combination with a dispenser of the type which contains a product to be dispensed under pressure within a predetermined normal pressure range, a bistable safety dispensing valve comprising:

(a) a valve stem having a longitudinal axis, an upper portion having an axially oriented product passage,

a lower portion having an axially oriented vent passage which has an opening communicating the vent passage with the dispensers interior at all times, a product port through the wall of the upper portion into the product passage, a vent port through the wall of the lower portion into the vent passage and spaced longitudinally of the opening toward the upper portion, and means between the product passage and the vent passage to prevent direct communication between them;

(b) means for mounting the dispensing valve to the dispenser such that the vent port is normally out of communication with the dispensers exterior, the vent passage is always in communication with the dispensers interior, the product port is normally out of communication with the dispensers interior, and the product passage extends to the dispensers eX- terior; and

(c) bistable spring means having a first and a second stable position, the bistable spring means being coupled to the valve stern such that:

(i) in the first stable position the valve stem is maintained against normal pressures in the dispenser in an unactuated position with the product port out of communication with the dispensers interior and the vent port out of communication with the dispensers exterior,

(ii) in the first stable position upon the application of a dispensing force on the valve stem exteriorly of the dispenser the valve stem is displaced against the force of the bistable spring means to communicate the product port with the interior of the dispenser,

(iii) with the presence of a predetermined pressure in excess of the normal pressure within the dispensers interior, the Valve stem is moved to a vent position with the dispensers exterior and the bistable spring means is moved to the second stable position; and (iv) in the second stable position the valve stem is maintained in the vent position regardless of the pressure within the dispensers interior.

12. The combination claimed in claim 11 wherein:

the bistable spring means includes a disc-shaped spring member dispensed to act between the valve stem and the dispenser.

13. The combination claimed in claim 12 wherein:

the disc-shaped spring member has a curvature which reverses between its stable positions to provide a force on the Valve stern to resist dispenser pressure in the first stable position and a force on the valve stern to augment dispenser pressure n-the second stable position and maintain the valve stem in the vent position.

14. The combination claimed in claim 13 wherein:

the disc-shaped spring member has a plurality of holes to accommodate movement of spring member material with movement of the spring.

15. The combination claimed in claim 14 wherein:

(a) the mounting means includes a housing receiving the bistable spring and the lower portion of the valve stem;

(b) the disc-shaped spring member includes a skirt disposed for guidance along the interior wall of the housing; and

(c) a return spring is provided between the housing and the valve stem for maintaining the product port out of communication with the interior of the dispenser until application of the dispensingforce.

16. The combination claimed in claim 11 wherein:

the mounting means and bistable spring means in the first stable position maintain the valve stem in a predetermined angular and axial orientation such that with the application of a dispensing force normal to the axis of the valve stem the valve stem is angularly displaced from the predetermined angular position to communicate the product port with the interior of the dispenser, and with the application of a dispensing force along the axis of the valve stem the valve stem is axially displaced from the predetermined axial position to communicate the product port with the interior of the dispenser.

17. The combination claimed in claim 16 wherein:

the mounting means includes a seal of yieldable material in receipt of the valve stem and in sealing relationship therewith, the seal being operable to permit the angular displacement of the valve stem to cornmunicate the product port with the interior of the dispenser.

18. The combination claimed in claim 17 wherein:

the bistable spring means includes a disc-shaped spring member disposed to act between the valve stem and the seal within the dispenser, the disc-shaped spring member having a curvature which reverses between References Cited UNITED STATES PATENTS 3,005,577 10/1961 Webster 222-397 3,161,324 12/1964 ONeill 22-396 X 3,519,172 7/1970 Bruce 222--396 3,527,388 9/1970 Cooprider Z22-396 X SAMUEL F. COLEMAN, Primary Examiner U.S. Cl. X.R. 

